Enhancement of Curie Temperature and Photoluminescent Properties of Ho1.98Sm0.02Sn2O7 and Ho1.90Er0.10Sn2O7 Smart Materials

Ho₂Sn₂O₇ powders doped with Er³⁺ and Sm³⁺ were directly synthesized using a solid state reaction method. Ho_1.98Sm_0.02Sn₂O₇ and Ho_1.90Er_0.10Sn₂O₇ were investigated using a TG/DTA thermal analysis system, scanning electron microscope (SEM), photoluminescence spectrophotometer (PL), X ray diffractometer (XRD), d33-meter and LCR-meter. As a result of the analyses, the thermal behaviour, crystal system, morphological structure, photoluminescence properties, elemental analysis, dielectric constant, piezoelectric properties and loss tangent of Ho_1.98Sm_0.02Sn₂O₇ and Ho_1.90Er_0.10Sn₂O₇ were obtained and discussed. According to XRD, the unit cell parameters for single-phase pyrochlores with a cubic crystal system are a = b = c = 10.374 Å and α = β = γ = 90°. The XRD patterns demonstrate that neither the type nor the amount of doping ion alters the unit cell parameter. The SEM images of Ho_1.98Sm_0.02Sn₂O₇ and Ho_1.90Er_0.10Sn₂O₇ reveal a regular morphology, with an average sample size ranging from 0.2 to 0.9 μm. The EDX analysis confirm the absence of impurity elements and showing that the theoretical and experimental element ratios are consistent with EDX analysis expectations. The emission spectrum of Ho_1.98Sm_0.02Sn₂O₇ and Ho_1.90Er_0.10Sn₂O₇ were shown typical transitions of Sm³⁺ and Er³⁺, respectively. Ho₂Sn₂O₇ doped with Sm³⁺ was found to yield a high dielectric constant (73.93), a high piezoelectric charge constant (0.75 pC/N), and a higher Curie temperature (772 °C). This suggests that Sm³⁺ ions enhance the Curie temperature and piezoelectric properties when introduced into the Ho₂Sn₂O₇ host crystal. The results indicate that Ho_1.98Sm_0.02Sn₂O₇ and Ho_1.90Er_0.10Sn₂O₇ are smart materials with multi-functional which have both piezoelectric properties and photoluminescent properties.