Physics and Chemistry of Minerals最新文献

{"title":"Experimental studies of charoite mineral transformations under thermal treatment","authors":"A. M. Ionov,&nbsp;O. I. Barkalov,&nbsp;D. A. Shulyatev,&nbsp;K. A. Gavrilicheva","doi":"10.1007/s00269-024-01282-9","DOIUrl":"10.1007/s00269-024-01282-9","url":null,"abstract":"<div><p>Phase transformations of the charoite mineral induced by thermal treatment at high temperatures were studied by simultaneous monitoring of the thermogravimetry, differential scanning calorimetry, and mass spectrometry curves up to its melting temperature range (~ 1300 °C). The chemical composition and phase state of the initial and melted samples were characterized using electron-probe micro-analysis, X-ray photoemission spectroscopy, X-ray powder diffraction, and Raman spectroscopy. It was demonstrated that continuous heating (10 °C/min) up to ~ 500 °C resulting in a mass loss of ~ 5 wt. % was due to crystallization water release and dehydroxylation, while oxygen release and carbonate inclusion decomposition were observed at a higher temperature. The endothermic peak with a heat effect of 82 J/g observed at 970 ÷ 1050 °C was attributed to the charoite-to-wollastonite transition detected by real-time X-ray powder diffraction in this temperature range. Above 1100 °C, another extended endothermic effect was fixed, which was presumably due to the formation of pseudowollastonite and pre-melting processes. The melting of the charoite sample using the floating zone technique resulted in its transformation to pseudowollastonite and caused a significant color change from lilac to rose pink.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":"51 2","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00269-024-01282-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140929666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Distribution of Sc3+ at the octahedral sites and its effect on the crystal structure of synthetic Sc-bearing clinozoisite on the Ca2Al3Si3O12(OH)-Ca2Al2ScSi3O12(OH) join","authors":"Mariko Nagashima,&nbsp;Yoji Morifuku,&nbsp;Boriana Mihailova","doi":"10.1007/s00269-024-01280-x","DOIUrl":"10.1007/s00269-024-01280-x","url":null,"abstract":"<div><p>Synthetic Sc-bearing clinozoisite on the Ca₂Al₃Si₃O₁₂(OH)-Ca₂Al₂Sc³⁺Si₃O₁₂(OH) join was studied by single-crystal X-ray diffraction to understand better the distribution of Sc³⁺ among the octahedral sites, M1-M3, and its effect on the structure of epidote-group minerals. Oxide starting materials of Ca₂Al₂(Al_1-<i>p</i>)Sc_<i>p</i>Si₃O_12.5 composition with <i>p</i> = 0.5 and 1.0 were employed, and clinozoisite was successfully synthesized at <i>P</i>_H2O = 1.2–1.5 GPa and <i>T</i> = 700–800 °C. The Sc content in clinozoisite varies and attains 0.61 atoms per formula unit (apfu) from <i>p</i> = 1.0 starting material. Two Sc-bearing clinozoisite crystals from the product of <i>p</i> = 0.5 starting material (Run 20) were used for X-ray crystal structural analysis. The unit-cell parameters are <i>a</i> = 8.8815(4), <i>b</i> = 5.6095(2), <i>c</i> = 10.1466(5) Å, β = 115.318(6)º, and <i>V</i> = 457.0(1) ų for 20B, and <i>a</i> = 8.885(1), <i>b</i> = 5.6119(4), <i>c</i> = 10.153(1) Å, β = 115.27(2)º, and <i>V</i> = 457.9(4) ų for 20D. The resulting Sc³⁺ occupancies among the octahedral sites are ^M1Al_1.0^M2Al_1.0^M3(Al_0.684(7)Sc³⁺_0.316) for the former and ^M1Al_1.0^M2Al_1.0^M3(Al_0.629(6)Sc³⁺_0.371) for the latter, i.e., Sc³⁺ exclusively occupies M3. The mean ionic distance of &lt; M3–O &gt; increases with increasing Sc content at M3, but it tends to be slightly shorter than the expected value using the regression line based on the structural data of synthetic Ca₂(Al, <i>Me</i>³⁺)₃Si₃O₁₂(OH) clinozoisite. It is due to the reduced distortion of M3O₆ octahedra caused by the short M3–O1 and M3–O8 distances. Although the angular variance ends up at a similar value to the Al-Fe³⁺ epidote, the variation of ∠O<i>i</i>–M3-O<i>i</i> angles is different. The Sc-bearing clinozoisite has greater ∠O1–M3–O1’, but smaller ∠O2–M3–O2’ and ∠O2–M3–O4 relative to Al-Fe³⁺ series ones. Due to different local chemical surroundings, multiple peaks are present in the OH stretching region of Raman spectra. Three OH-stretching peaks, centered at 3342, 3382, and 3468 cm⁻¹ are assigned to the local configuration O10–H···O4–(^M1Al^M1Al^M3Sc³⁺) and O10–H···O4–(^M1Al^M1Al^M3Al), and O10–H···O2, respectively.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":"51 2","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00269-024-01280-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of rare earth elements in synthetic and natural monazite and xenotime by visible-to-shortwave infrared reflectance spectroscopy","authors":"A. H. Dijkstra,&nbsp;W. H. Bakker,&nbsp;F. Deon,&nbsp;C. Marcatelli,&nbsp;M. P. Plokker,&nbsp;H. T. Hintzen","doi":"10.1007/s00269-024-01284-7","DOIUrl":"10.1007/s00269-024-01284-7","url":null,"abstract":"<div><p>To support the role of proximal and remote sensing in geological rare earth element (REE) resource exploration, we studied the reflectance spectroscopy of synthetic single- and mixed-REE phosphate phases. Synthesis yielded monazite for the elements La to Gd, and xenotime for Dy to Lu and Y. Visible-to-shortwave infrared (350–2500 nm) reflectance spectra of synthetic single-REE monazites and xenotimes can be used to identify the ions responsible for the absorption features in natural monazites and xenotimes. Nd³⁺, Pr³⁺ and Sm³⁺ produce the main absorption features in monazites. In natural xenotime, Dy³⁺, Er³⁺, Ho³⁺ and Tb³⁺ ions cause the prevalent absorptions. The majority of the REE-related absorption features are due to photons exciting electrons within the 4f subshell of the trivalent lanthanide ions to elevated energy levels resulting from spin-orbit coupling. There are small (&lt; 20 nm) shifts in the wavelengths of these absorptions depending on the nature of the ligands. The energy levels are further split by crystal field effects, manifested in the reflectance spectra as closely spaced (∼ 5–20 nm) multiplets within the larger absorption features. Superimposed on the electronic absorptions are vibrational absorptions in the H₂O molecule or within [OH]⁻, [CO₃]²⁻ and [PO₄]³⁻ functional groups, but so far only the carbonate-related spectral features seem usable as a diagnostic tool in REE-bearing minerals. Altogether, our study creates a strengthened knowledge base for detection of REE using reflectance spectroscopy and provides a starting point for the identification of REE and their host minerals in mineral resources by means of hyperspectral methods.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":"51 2","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00269-024-01284-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In situ X-ray and IR probes relevant to Earth science at the Advanced Light Source at Lawrence Berkeley Laboratory","authors":"Martin Kunz,&nbsp;Katherine Armstrong,&nbsp;Harold Barnard,&nbsp;Hans A. Bechtel,&nbsp;Samantha C. Couper,&nbsp;Bora Kalkan,&nbsp;Harry Lisabeth,&nbsp;Alastair A. MacDowell,&nbsp;Lowell Miyagi,&nbsp;Dilworth Y. Parkinson,&nbsp;Nobumichi Tamura,&nbsp;Quentin Williams","doi":"10.1007/s00269-024-01278-5","DOIUrl":"10.1007/s00269-024-01278-5","url":null,"abstract":"<div><p>Access to synchrotron X-ray facilities has become an important aspect for many disciplines in experimental Earth science. This is especially important for studies that rely on probing samples in situ under natural conditions different from the ones found at the surface of the Earth. The non-ambient condition Earth science program at the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, offers a variety of tools utilizing the infra-red and hard X-ray spectrum that allow Earth scientists to probe Earth and environmental materials at variable conditions of pressure, stress, temperature, atmospheric composition, and humidity. These facilities are important tools for the user community in that they offer not only considerable capacity (non-ambient condition diffraction) but also complementary (IR spectroscopy, microtomography), and in some cases unique (Laue microdiffraction) instruments. The availability of the ALS’ in situ probes to the Earth science community grows especially critical during the ongoing dark time of the Advanced Photon Source in Chicago, which massively reduces available in situ synchrotron user time in North America.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":"51 2","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00269-024-01278-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140809566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nefedovite, Na5Ca4(PO4)4F: thermal evolution, phase transition and crystal structure refinement","authors":"Margarita S. Avdontceva,&nbsp;Andrey P. Shablinskii,&nbsp;Maria G. Krzhizhanovskaya,&nbsp;Sergey V. Krivovichev,&nbsp;Andrey A. Zolotarev,&nbsp;Vladimir N. Bocharov,&nbsp;Natalia S. Vlasenko,&nbsp;Evgenia Yu. Avdontseva,&nbsp;Victor N. Yakovenchuk","doi":"10.1007/s00269-024-01276-7","DOIUrl":"10.1007/s00269-024-01276-7","url":null,"abstract":"<div><p>Nefedovite, Na₅Ca₄(PO₄)₄F, has been investigated by in situ high-temperature powder (30–690 °C) and single crystal (27–827 °C) X-ray diffraction and Raman spectroscopy. Nefedovite is tetragonal, space group <i>I</i>-4, <i>a</i> = 11.6560(2), <i>c</i> = 5.4062(2) Å, <i>V</i> = 734.50(2) ų (<i>R</i>_<i>1</i> = 0.0149). Nefedovite is a 1<i>D</i> antiperovskite, since its crystal structure contains chains of corner-sharing anion-centered [FCa₄Na₂]⁹⁺ octahedra. The chains are parallel to the <i>c</i> direction. Nefedovite is stable up to 727 °C and undergoes a displacive phase transition in the temperature range 277–327 <i>°</i>C. With increasing temperature, the PO₄ tetrahedra in the crystal structure of nefedovite gradually rotate around the imaginary fourfold inversion axes aligning the O2^…O3 edge parallel to [110], which ultimately leads to the appearance of the mirror plane perpendicular to the <i>c</i> direction and the change of space group from <i>I</i>-4 (82) to <i>I</i>4/<i>m</i> (87). The crystal structure of nefedovite expands strongly anisotropically with the direction of the maximum thermal expansion oriented perpendicular to the chains of anion-centered octahedra. The information-based structural complexity analysis demonstrates that both low- and high-temperature modifications of nefedovite are structurally simple with the <i>I</i>_G,total value less than 100 bits per unit cell. The structural complexity decreases along the phase transition, which is typical for displacive phase transitions.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":"51 2","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140675296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal evolution of metamict davidite-(La) from the Radium Hill, Australia: recrystallization and thermal expansion","authors":"Ruiqi Chen,&nbsp;Oleg I. Siidra,&nbsp;Valery L. Ugolkov,&nbsp;Vera A. Firsova,&nbsp;Natalia S. Vlasenko,&nbsp;Angel M. Arevalo-Lopez,&nbsp;Marie Colmont,&nbsp;Vladimir N. Bocharov","doi":"10.1007/s00269-024-01274-9","DOIUrl":"10.1007/s00269-024-01274-9","url":null,"abstract":"<div><p>Aside from its economic value, davidite and its synthetic analogs may have potential applications in materials science. The unique properties of the crichtonite group minerals, including davidite-(La), make them attractive candidates for high-level waste (HLW) immobilization. We studied the thermal evolution of the metamict davidite-(La) from the Radium Hill, Australia. The investigation of the temperature-induced crystallization process was conducted, and the thermal expansion coefficients (TEC) for the recrystallized davidite (RD) were determined for the first time. Our results demonstrate that RD has relatively low TEC indicating its thermophysical stability. The following TECs of davidite- (La) for the temperature range 25–1200 °C were obtained: <span>(overline{mathrm{alpha }})</span> _<i>a</i> = <span>(overline{mathrm{alpha }})</span> _<i>b</i> = 9.96 (3) × 10^–6 ºC⁻¹; <span>(overline{mathrm{alpha }})</span> _<i>c</i> = 10.79 (4) × 10^–6 ºC⁻¹. The character of the thermal expansion is in agreement with the structure characterized by layers stacked along the <i>c</i> axis. The volume TEC α_<i>V</i> = 24.81 (47)—36.80 (48) × 10^–6 ºC⁻¹. Davidite-(La) exhibits an almost isotropic thermal expansion and shows one of the most superior thermal performances in comparison to the other mineral-like phases utilized for the immobilization of HLW.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":"51 2","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140676115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pressure-induced large volume collapse and possible spin transition in HP-PdF2-type FeCl2","authors":"Yao Yao,&nbsp;Xi Liu,&nbsp;Xueyan Du,&nbsp;Lili Zhang,&nbsp;Hongsheng Yuan","doi":"10.1007/s00269-024-01271-y","DOIUrl":"10.1007/s00269-024-01271-y","url":null,"abstract":"<div><p>Iron hydroxide FeO₂H_<i>x</i> (<i>x</i> ≤ 1) and ferrous iron chloride FeCl₂ can adopt the HP-PdF₂-type (space group: <span>(P{a_{overline 3 }})</span>, <i>Z</i> = 4) structure in the lowermost mantle, potentially contributing to the geochemical cycles of hydrogen and chlorine within Earth’s deep interior, respectively. Here we investigate the high-pressure behavior of HP-PdF₂-type FeCl₂ by X-ray diffraction (XRD) and Raman measurements in laser-heated diamond anvil cells. Our results show that HP-PdF₂-type FeCl₂ can be formed at 60‒67 GPa and 1650‒1850 K. Upon cold decompression, the diffraction peaks at pressures above 10 GPa can be indexed to the HP-PdF₂-type structure. Intriguingly, the calculated cell volumes reveal a remarkable decrease of Δ<i>V</i> / <i>V</i> = ∼ 14% between 36 and 40 GPa, which is possibly caused by a pressure-induced spin transition of Fe²⁺ (HS: high-spin → LS: low-spin). We also observe distinct changes in Raman spectra at 33‒35 GPa, practically coinciding with the onset pressures of isostructural phase transition in XRD results. Our observations combined with previous studies conducted at megabar pressures suggest that HP-PdF₂-type FeCl₂, with a wide pressure stability range, if present in subducting slabs, could facilitate the transport of chlorine from the middle lower mantle to the outer core.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":"51 2","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140566128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Crystal structure of calcite-type Ca1–xMnxCO3 solid solution by X-ray diffraction and Raman spectroscopy","authors":"Shanrong Zhang,&nbsp;Wen Liang,&nbsp;Mengzeng Wu,&nbsp;Qifa Zhong,&nbsp;Dawei Fan","doi":"10.1007/s00269-024-01269-6","DOIUrl":"10.1007/s00269-024-01269-6","url":null,"abstract":"<div><p>To investigate the quantitative relationship between the crystal structure and composition of Mn-bearing calcite, the solid solutions of Ca_1–<i>x</i>Mn_<i>x</i>CO₃ (<i>x</i> = 0.1, 0.3, 0.5, 0.7, 0.9) with continuous MnCO₃ mol% content were synthesized at 1 GPa and 700 °C using high-purity CaCO₃ and MnCO₃ powders as starting materials. The run products were analysized by electron probe, powder X-ray diffraction and Raman spectroscopy. The CaO wt% and MnO wt% of the resulting products are consistent with the expected compositions. The powder X-ray diffraction results show that the products are single phase without any impurities. All diffraction peaks of samples with varying MnCO₃ mol% contents can be indexed by the calcite-type structure carbonates ACO₃ (<i>R-3c</i> space group; A is a divalent cation), confirming the previous results that there is the completely continuous solid solution between CaCO₃ and MnCO₃ end members. The unit-cell parameters and volumes of the solid solutions decrease as the MnCO₃ mol% content increases, presenting a linear relationship of Ca–Mn ideal miscibility, which is perfectly consistent with the rigid body model of A-site substitution in ACO₃. Besides, as MnCO₃ mol% content increases, the bond distance of A–O decreases linearly, while the bond distance of C–O changes like a parabola. Therefore, the addition of Mn makes the bond distance of A–O shorten, resulting in the decrease of unit-cell parameters and volumes for Ca_1–<i>x</i>Mn_<i>x</i>CO₃. Furthermore, two exterior vibrations (T and L) of the crystal lattice and two internal vibrations (ν₄ and ν₁) within the CO₃²⁻ unit are assigned in the Raman spectra of these solid solutions. The characteristic vibration modes T, L, and ν₄ as a whole increase with the increasing of MnCO₃ mol% content, whereas the characteristic vibration mode ν₁ as a whole decreases with the increase of MnCO₃ mol% content. These variations in Raman vibration modes are related to the radius of substituted ions.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":"51 2","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140153737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermodynamic mixing properties of disordered alkali feldspar solid-solution from Na–K partitioning and low-temperature calorimetry","authors":"D. Heuser,&nbsp;E. Petrishcheva,&nbsp;F. Ingegneri,&nbsp;C. L. Lengauer,&nbsp;E. Dachs,&nbsp;C. Hauzenberger,&nbsp;R. Abart","doi":"10.1007/s00269-024-01270-z","DOIUrl":"10.1007/s00269-024-01270-z","url":null,"abstract":"<div><p>The equilibrium partitioning of Na and K between alkali feldspar and NaCl–KCl salt melt was determined at 800 <span>(^circ)</span>C, 850 <span>(^circ)</span>C, 900 <span>(^circ)</span>C, 950 <span>(^circ)</span>C and 1000 <span>(^circ)</span>C and close to ambient pressure. Four different natural gem-quality alkali feldspars with low degree of Al–Si ordering covering the range from orthoclase to high sanidine and with slightly different minor element concentrations were used as starting materials. The partitioning curves obtained for the four feldspars are indistinguishable indicating that Na–K partitioning independent of the differences of Al–Si ordering state and minor element concentrations existing amongst these feldspars. A sub-regular two parameter Margules type solution model was fitted to the partitioning data, and the excess Gibbs energy describing the thermodynamic non-ideality of the alkali feldspar solid-solution and the respective Margules parameters <span>(W_{text {g}text {K}})</span> and <span>(W_{text {g}text {Na}})</span> including their temperature dependence expressed as <span>(W_g=W_h-TW_s)</span> were determined: </p><div><div><span>$$begin{aligned} W_{text {g}text {K}}&amp;= 19754 pm 3140 Jcdot ,,{hbox {mol}},,^{-1} - T cdot 2.33 pm 2.67 Jcdot ,,{hbox {mol}},,^{-1}cdot K^{-1} W_{text {g}text {Na}}&amp;= 14916 pm 4272 Jcdot ,,{hbox {mol}},,^{-1} - T cdot 3.55 pm 3.64 Jcdot {hbox {mol}},,^{-1}cdot K^{-1} end{aligned}$$</span></div></div><p>The corresponding solvus has a critical temperature slightly above 650 <span>(^circ)</span>C and is well comparable with earlier direct experimental determinations of the low-sanidine-albite solvus curve. Comparison of the vibrational excess entropy determined from low-temperature heat capacity measurements with the total excess entropy derived from the temperature dependence of the excess Gibbs energy yields a negative configurational contribution to the excess entropy pointing towards short-range Na–K ordering on the alkali site.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":"51 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00269-024-01270-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139978708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal evolution of the metamict fergusonite-(Y)","authors":"Ruiqi Chen,&nbsp;Oleg I. Siidra,&nbsp;Vera A. Firsova,&nbsp;Valery L. Ugolkov,&nbsp;Natalia S. Vlasenko,&nbsp;Vladimir N. Bocharov,&nbsp;Angel M. Arevalo-Lopez,&nbsp;Marie Colmont,&nbsp;Igor V. Tokarev","doi":"10.1007/s00269-023-01263-4","DOIUrl":"10.1007/s00269-023-01263-4","url":null,"abstract":"<div><p>The metamict fergusonite-(Y) with the formula (Y_0.70<i>Ln</i>_0.20Ca_0.13U_0.02Th_0.02)_∑1.07(Nb_0.72Ta_0.17W_0.06Ti_0.04)_∑1(O_3.97(OH)_0.11F_0.08Cl_0.03) · 2.12H₂O from the Blyumovskaya Pit, Ilmeny Mountains (Russia) was studied by the means of high-temperature X-ray diffraction, thermal analysis, Raman spectroscopy and microprobe analysis. Thermal expansion was studied for both tetragonal (<i>α</i>-fergusonite) and monoclinic (<i>β</i>-fergusonite) polymorphs. The expansion of <i>β</i>-fergusonite is anisotropic and strongly negative along the <i>α</i>₃₃. In contrast, <i>α</i>-fergusonite exhibits a relatively isotropic thermal expansion upon heating. The volume CTE (<i>α</i>_<i>V</i>) for <i>β</i>-fergusonite varies in the range 22.87(94)–75.4(2.5) × 10^–6 ºC⁻¹, whereas <i>α</i>-fergusonite has <i>α</i>_<i>V</i> = 32.33(57)–31.66(49) × 10^-⁶ ºC⁻¹ in the temperature range 850–1200 °C. After heating to 1100 °C, the mineral develops a porous texture, and the radioactivity is reduced by 37%, which can be attributed to the partial volatilization of some radionuclides. In situ experiments revealed the complete sequence of the thermal evolution of the metamict fergusonite-(Y) for the first time.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":"51 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139768229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}