按照0.71Pb(Mg1/3Nb2/3)O3-0.26Pb Ti O3-0.03Pb(Er1/2Nb1/2)O3化学式所示组分比例,采用分步高温固相反应合成出Er3+掺杂PMNT多晶,通过熔体坩埚下降法生长出尺寸φ25 mm×100 mm的Er3+掺杂PMNT晶体,Er3+离子以三元固溶体组元方式被...按照0.71Pb(Mg1/3Nb2/3)O3-0.26Pb Ti O3-0.03Pb(Er1/2Nb1/2)O3化学式所示组分比例,采用分步高温固相反应合成出Er3+掺杂PMNT多晶,通过熔体坩埚下降法生长出尺寸φ25 mm×100 mm的Er3+掺杂PMNT晶体,Er3+离子以三元固溶体组元方式被掺杂进入钙钛矿相铁电体晶格;测试了Er3+掺杂PMNT晶片的介电、压电与铁电性能以及上转换发光性能。结果表明,Er3+掺杂PMNT晶体呈现跟三方相纯PMNT晶体相近的介电、压电与铁电性能;在980 nm激发光作用下,该掺杂晶体呈现出Er3+离子特有的较强上转换荧光发射,并且极化后掺杂晶体的上转换发光强度得到增强。展开更多
It is difficult for the growth of relaxor ferroelectric single crystal (1 x ) Pb(Mg 1/3 Nb 2/3 )O 3 x PbTiO 3 (abbreviated as PMNT).The first reason is that there are four oxides as raw materials which are easily resu...It is difficult for the growth of relaxor ferroelectric single crystal (1 x ) Pb(Mg 1/3 Nb 2/3 )O 3 x PbTiO 3 (abbreviated as PMNT).The first reason is that there are four oxides as raw materials which are easily result in the nonstoichiometry and inhomogeneity for the single crystals,the second is that the pyrochlore phases appear easily for general growth condition that will reduce the dielectric and piezoelectric performance of PMNT single crystals,and the third is that the platinum crucible is easily leaked at the melting temperature of PMNT.A feasible technique has been used for the growth of PMNT single crystals after we researched the stability,structure and relation of PMN PT phases at high temperature.Now we can fabricate the large size and high quality of PMNT single crystals by a modified Bridgman technique.展开更多
Relaxor ferroelectric single crystals PMNT with the size of φ40 mm×80 mm have been grown by a modified Bridgman method and their ferroelectric and piezoelectric properties have been characterized. The properties...Relaxor ferroelectric single crystals PMNT with the size of φ40 mm×80 mm have been grown by a modified Bridgman method and their ferroelectric and piezoelectric properties have been characterized. The properties varied with the compositions and cut types. On the (001) cut, PMNT76/24 single crystals exhibited a dielectric constant ε of about 3 400, a dielectric loss of tanδ 【0.7%, a piezoelectric constant d33 of 980 pC/N, an electromechanical coupling factor kt of 0.55 and Tc of about 110℃. whereas the properties of PMNT67/33 single crystals on (001) cut were betler: e of about 5 300, tan5 【0.6%, d33 up to 3 000 pC/N, kt 0.64, K33 0.93 and Tc of about 150℃. The piezoelectric properties on other cuts such as (110) and (111) were much lower than those on the (001) cut. The rhombohedral PMNT crystals grown by this method showed more excellent piezoelectric properties than those grown by high temperature solution method and higher value of kt than the rhombohedral PZNT single crystals. it has also展开更多
High-performance relaxor ferroelectric single crystals Pb(Mg<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub>-PbTiO<sub>3</sub> have been grown successfully by a modified Bri...High-performance relaxor ferroelectric single crystals Pb(Mg<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub>-PbTiO<sub>3</sub> have been grown successfully by a modified Bridgman method. They have the size of 25×25×50mm<sup>3</sup> and are of pure perovskite phases with tetragonal or rhombohedral structures. Their {001} faces appear dominantly, which can be interpreted by the model of anionic coordination polyhedral growth units. Main macro defects observed under optical microscopes and SEM can be reduced or removed by improving growth parameters after understanding their formation mechanism. 71° or 109° macrodomains in rhombohedral PMNT 76/24 crystals and 90° macrodomains in tetragonal PMNT 65/35 crystals have been observed by optical microscopes. It has been found that the transition from microdomains to macrodomains can be induced by compositions. Both the imaging mechanism of non-180° domains and the relation between domain configurations and ferroelectric phase transition have been analyzed.展开更多
The features of the single crystals 0.76PMN-0.24PT in dielectric, ferroelectric, pyroelectric properties and domain structures indicate that they are located between typical ferroelectrics and normal ones. The unpoled...The features of the single crystals 0.76PMN-0.24PT in dielectric, ferroelectric, pyroelectric properties and domain structures indicate that they are located between typical ferroelectrics and normal ones. The unpoled crystals present a transitional domain configuration between microdomains and typical macrodomains while the crystals on (001) cuts undergo field-induced phase transition under poling, showing two special temperature points Td and Tm during the succedent heating procedure. The dielectric constant starts to decrease drastically at Td during cooling, or the transformation from induced macrodomain to transitional domain takes place at Td during heating. Ferroelectric-paraelectric phase transition or depolarization continues within the whole temperature range of Td-Tm, where ferroelectric phase in the form of transitional macrodomains coexists with paraelectric phase. Then the crystals macroscopically transoform into paraelectric phase containing ferroelectric microdomains at a temperature展开更多
文摘It is difficult for the growth of relaxor ferroelectric single crystal (1 x ) Pb(Mg 1/3 Nb 2/3 )O 3 x PbTiO 3 (abbreviated as PMNT).The first reason is that there are four oxides as raw materials which are easily result in the nonstoichiometry and inhomogeneity for the single crystals,the second is that the pyrochlore phases appear easily for general growth condition that will reduce the dielectric and piezoelectric performance of PMNT single crystals,and the third is that the platinum crucible is easily leaked at the melting temperature of PMNT.A feasible technique has been used for the growth of PMNT single crystals after we researched the stability,structure and relation of PMN PT phases at high temperature.Now we can fabricate the large size and high quality of PMNT single crystals by a modified Bridgman technique.
文摘Relaxor ferroelectric single crystals PMNT with the size of φ40 mm×80 mm have been grown by a modified Bridgman method and their ferroelectric and piezoelectric properties have been characterized. The properties varied with the compositions and cut types. On the (001) cut, PMNT76/24 single crystals exhibited a dielectric constant ε of about 3 400, a dielectric loss of tanδ 【0.7%, a piezoelectric constant d33 of 980 pC/N, an electromechanical coupling factor kt of 0.55 and Tc of about 110℃. whereas the properties of PMNT67/33 single crystals on (001) cut were betler: e of about 5 300, tan5 【0.6%, d33 up to 3 000 pC/N, kt 0.64, K33 0.93 and Tc of about 150℃. The piezoelectric properties on other cuts such as (110) and (111) were much lower than those on the (001) cut. The rhombohedral PMNT crystals grown by this method showed more excellent piezoelectric properties than those grown by high temperature solution method and higher value of kt than the rhombohedral PZNT single crystals. it has also
基金Project supported by the National Natural Science Foundation of China (No. 59995520), the Chinese Academy of Sciences and Shanghai Municipal Government.
文摘High-performance relaxor ferroelectric single crystals Pb(Mg<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub>-PbTiO<sub>3</sub> have been grown successfully by a modified Bridgman method. They have the size of 25×25×50mm<sup>3</sup> and are of pure perovskite phases with tetragonal or rhombohedral structures. Their {001} faces appear dominantly, which can be interpreted by the model of anionic coordination polyhedral growth units. Main macro defects observed under optical microscopes and SEM can be reduced or removed by improving growth parameters after understanding their formation mechanism. 71° or 109° macrodomains in rhombohedral PMNT 76/24 crystals and 90° macrodomains in tetragonal PMNT 65/35 crystals have been observed by optical microscopes. It has been found that the transition from microdomains to macrodomains can be induced by compositions. Both the imaging mechanism of non-180° domains and the relation between domain configurations and ferroelectric phase transition have been analyzed.
文摘The features of the single crystals 0.76PMN-0.24PT in dielectric, ferroelectric, pyroelectric properties and domain structures indicate that they are located between typical ferroelectrics and normal ones. The unpoled crystals present a transitional domain configuration between microdomains and typical macrodomains while the crystals on (001) cuts undergo field-induced phase transition under poling, showing two special temperature points Td and Tm during the succedent heating procedure. The dielectric constant starts to decrease drastically at Td during cooling, or the transformation from induced macrodomain to transitional domain takes place at Td during heating. Ferroelectric-paraelectric phase transition or depolarization continues within the whole temperature range of Td-Tm, where ferroelectric phase in the form of transitional macrodomains coexists with paraelectric phase. Then the crystals macroscopically transoform into paraelectric phase containing ferroelectric microdomains at a temperature
