Browsing by Author "Öztürk, Esra"

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Citation - WoS: 1
Citation - Scopus: 1
Enhancement of Curie Temperature and Photoluminescent Properties of Ho1.98sm0.02sn2o7 and Ho1.90er0.10sn2o7 Smart Materials
(SPRINGER, 2025) Öztürk, Esra; Kalaycıoğlu Özpozan, Nilgün; Kalem, Volkan
Ho2Sn2O7 powders doped with Er3+ and Sm3+ were directly synthesized using a solid state reaction method. Ho1.98Sm0.02Sn2O7 and Ho1.90Er0.10Sn2O7 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 Ho1.98Sm0.02Sn2O7 and Ho1.90Er0.10Sn2O7 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 & Aring; and alpha = beta = gamma = 90 degrees. The XRD patterns demonstrate that neither the type nor the amount of doping ion alters the unit cell parameter. The SEM images of Ho1.98Sm0.02Sn2O7 and Ho1.90Er0.10Sn2O7 reveal a regular morphology, with an average sample size ranging from 0.2 to 0.9 mu m. 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 Ho1.98Sm0.02Sn2O7 and Ho1.90Er0.10Sn2O7 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 degrees C). This suggests that Sm3+ ions enhance the Curie temperature and piezoelectric properties when introduced into the Ho2Sn2O7 host crystal. The results indicate that Ho1.98Sm0.02Sn2O7 and Ho1.90Er0.10Sn2O7 are smart materials with multi-functional which have both piezoelectric properties and photoluminescent properties.
Enhancement of Curie Temperature and Photoluminescent Properties of Nd2mo2o7, Ho2mo2o7, and Gd2mo2o7
(WILEY, 2020) Öztürk, Esra; Kalem, Volkan; Karacaoğlu, Erkul
For Nd1.90Er0.10Mo2O7, Ho1.90Er0.10Mo2O7, and Gd1.98Eu0.02Mo2O7 nominal compositions, oxide compounds were prepared by solid-state reaction method. X-ray diffraction measurements show that molybdenum oxides formed cubic phase except for Nd1.90Er0.10Mo2O7. Scanning electron microscopy was used to observe their microstructure and elemental analysis. The photoluminescence properties of the materials, the excitation and emission spectra and the decay curve, were investigated using photoluminescence spectrophotometer. Dielectric and piezoelectric properties of the ptoluminescent materials, the dielectric constant, dielectric loss, piezoelectric constant, and Curie temperature, were measured for electrical characterization. Nd1.90Er0.10Mo2O7, Ho1.90Er0.10Mo2O7, and Gd1.98Eu0.02Mo2O7 materials show both photoluminescence and piezoelectric properties.
Investigation of Piezoelectric and Photoluminescence Properties of the Multifunctional La2sn2o7 and Ho2sn2o7 Pyrochlore Smart Materials Doped With Eu3+
(Elsevier, 2025) Öztürk, Esra; Kalem, Volkan; Ozpozan, Nilgun; Dayan, Serkan
RE2-xEuxSn2O7 (RE:La3+ and Ho3+, x:0.10) materials were synthesized having both pholuminescence and piezoelectric properties using with solid state reaction method at various reaction temperature and heating duration in open atmosphere. The thermal behaviors, crystal system, surface morphology, EDX analysis, Curie tempereture, photoluminescent properties, dielectric and piezoelectric properties of Eu3+ ions doped La2Sn2O7 and Ho2Sn2O7 were investigated. Both multi-functional smart materials show dielectric, piezoelectric properties and photoluminescence properties which is responsible transitions of doping Eu3+ ions.
Citation - WoS: 4
Citation - Scopus: 4
The Investigation of the Effect of La3+, Eu3+, and Sm3+ Ions on Photoluminescence and Piezoelectric Behavior of Re1.90y0.10zr2o7 (re: Eu, Sm and Y: La, Sm, Eu) Pyrochlore-Based Multifunctional Smart Advanced Materials
(WILEY, 2024) Öztürk, Esra; Kalaycioglu Ozpozan, Nilgun; Kalem, Volkan
A series of compounds with the general formula RE1.90Y0.10Zr2O7 (where RE includes Eu, Sm and Y includes La, Sm, Eu) were synthesized using a solid-state reaction method. These compounds were analyzed through differential thermal analysis (DTA), thermogravimetric analysis (TG), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). Additionally, their dielectric constant, loss tangent, piezoelectric charge constant, and Curie temperature were measured using an LCR meter, d(33) meter, and TG/DTA. X-ray diffraction results indicated that all samples crystallize in a cubic pyrochlore structure. Photoluminescence studies revealed that Eu3+ ions predominantly contribute to the emission, whether as activators or co-activators. Among the phosphors, Eu1.90La0.10Zr2O7 exhibited a significantly longer afterglow compared to Sm1.90Eu0.10Zr2O7 and Eu1.90Sm0.10Zr2O7. Conversely, Sm1.90Eu0.10Zr2O7 demonstrated luminescence intensity that was 20 times greater than that of Eu1.90La0.10Zr2O7 and Eu1.90Sm0.10Zr2O7. Furthermore, all samples with characteristic Eu3+ emissions also exhibited piezoelectric properties. Curie temperature (T-c) of Eu1.90La0.10Zr2O7, Sm1.90Eu0.10Zr2O7, and Eu1.90Sm0.10Zr2O7 are 770 degrees C, 830 degrees C, and 845 degrees C, respectively. Therefore, Sm3+ ion improves piezoelectric properties and Curie temperature when doping into the Eu2Zr2O7 host crystal.
Citation - WoS: 16
Citation - Scopus: 16
Photoluminescence and Piezoelectric Behaviour of Y2zr2o7 Pyrochlore-Based Multifunctional Materials and the Influence of Eu3+ and Sm3+
(WILEY, 2020) Öztürk, Esra; Karacaoğlu, Erkul; Kalem, Volkan
Y2Zr2O7-doped with Eu3+ and Sm3+ phosphors were prepared for the first time as multifunctional smart materials using a solid-state reaction method at 1400(o)C. Thermal behaviour, crystal structure, surface morphology, and elemental analysis were characterized using thermogravimetric (TG) and differential thermal (DTA) analyses, X-ray diffraction (XRD) and scanning electron microscope equipped with energy-dispersive X-ray spectroscopy (SEM-EDX). Experimental results revealed that both phosphors have a pyrochlore structure with a cubic crystal system. Photoluminescence properties were also measured and red emission was observed from Y1.90Eu0.10Zr2O7 and Y1.90Sm0.10Zr2O7 phosphors. Dielectric constant, loss tangent, piezoelectric charge constant, and Curie temperature of all the samples were determined using an LCR-meter, d(33)-meter, and TG/DTA. Eu doping in Y2Zr2O7 resulted in a high dielectric constant (9.61) and low loss tangent (1.67%) values, whereas high piezoelectric charge constant (0.68 pC/N) and high Curie temperature (820 degrees C) could be obtained using Sm-doped Y2Zr2O7.
Citation - WoS: 3
Citation - Scopus: 3
Photoluminescence and Piezoelectric Behaviour of Yb2s2o7 Pyrochlore Based Multifunctional Smart Advanced Materials and the Influence of Lu3+ and Eu3+
(ELSEVIER, 2021) Öztürk, Esra; Karacaoğlu, Erkul; Kalem, Volkan; Özpozan, Nilgün
In this study, Yb1.98Lu0.02Sn2O7 and Yb1.90Eu0.10Sn2O7 were produced by solid state reaction method. The characterization of the samples was achieved by thermal analysis (TG/DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM-EDX), photoluminescence spectrophotometer (PL), LCR-meter and d(33)m. Thermal behaviours, crystal structures, surface morphology, elemental analysis, photoluminescence properties, deielectric and piezoelectric properties and Curie temperature of Yb1.98Lu0.02Sn2O7 and Yb1.90Eu0.10Sn2O7 were investigated. X-ray diffraction datas indicate that the formation of cubic crystal structures were achieved for both materials. The photoluminescence and electrical measurements showed that Yb(1.98)Lu(0.02)Sn(2)O(7 )and Yb1.90Eu0.10Sn2O7 have both luminescent and piezoelectric properties.