Solution Bridgman Method Research Articles

Temperature Dependence of Domain Structure in (K0.17Na0.83)NbO3 Lead Free Piezoelectric Single Crystal Grown by Bridgman Method

Lead free piezoelectric single crystals of (K0.17Na0.83)NbO3 have been successfully grown by the solution Bridgman method. The chemical composition of the obtained single crystal was determined by electron probe microanalysis (EPMA), showing that the K/Na ration is derivate from the theoretical ratio. The crystal was examined also by X-ray diffraction and dielectric measurements. The optical study of (K0.17Na0.83)NbO3 single crystal shown three phase transition at 223°C, 412°C and 472°C in heating and at 198°C, 408°C and 478°C during cooling, while dielectric measurements performed on (K0.17Na0.83)NbO3 single crystal exhibited phase transitions at 206°C and 424°C, respectively.

Dielectric and Piezoelectric Properties of Pb[(In1/2Nb1/2)0.24(Mg1/3Nb2/3)0.42Ti0.34]O3 Single Crystals

The dielectric and piezoelectric properties of the 0.24Pb(In1/2Nb1/2)O3-0.42Pb(Mg1/3Nb2/3)-0.34PbTiO3 (PIMNT 24/42/34) ternary system was investigated in order to improve thermal stability and voltage-proof nature of electrical properties. A PIMNT 24/42/34 single crystal 25 mm in diameter and 30 mm in length was successfully grown by the solution Bridgman method using PbO-B2O3 flux; the highest temperature was 1250°C and the growth rate was 0.4 mm/h. The Curie temperature, Tc, and the phase transition temperature between rhombohedral and tetragonal phases, Trt, were 184°C and 89°C, respectively. The dielectric constant after poling, ε33T/ε0 = 4,900, electromechanical coupling factors for the sliver mode, k33'=80.3%, piezoelectric constant, d33=2,200 pC/N, and coercive field, Ec=6.8 kV/cm, were confirmed. Moreover, k33' was very stable until about 80°C because of the high Trt.

Growth and electrical properties of Pb(In 0.5Nb 0.5)O 3–PbTiO 3 crystals by the solution Bridgman method

Single crystals of 0.65Pb(In 0.5Nb 0.5)O 3–0.35PbTiO 3 (PINT) have been successfully grown by the solution Bridgman method using PbO–B 2O 3 flux. The largest PINT (65/35) single crystal with size 22 mm×8 mm×6 mm, colored light yellow and translucent, was obtained. An interesting phenomenon observed in the study is the following: some regular-shaped small black In 2O 3 crystals with sizes from 2 mm×2 mm×2 mm to 3 mm×4 mm×5 mm were found in the final coagulation. The result of differential thermal analysis (DTA) in a closed-tube system shows the eutectic character of the PINT (65/35) binary system which is fit for growth by the Bridgman technique. Dielectric constant gets up to the maximum value ( > 11000 ) at 294 °C, the Curie temperature. The rhombohedral–tetragonal phase transition temperature ( T rt), 219 °C, may be observed, which is much higher than that of (1− x)Pb(Mg 1/3Nb 2/3)O 3– xPbTiO 3(PMNT) (∼60 °C) and (1− x)Pb(Zn 1/3Nb 2/3)O 3– xPbTiO 3 (PZNT) (∼80 °C) single crystal near the morphotropic phase boundary (MPB). The piezoelectric properties were measured on the (1 1 1) plane of achievable crystals and showed d 33 = 200 pC / N and k t = 37.8 % . Good piezoelectric properties on the (0 0 1) plates are anticipated.

Crystal Growth of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 and Pb(Sc1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 Piezoelectric Single Crystals Using the Solution Bridgman Method

The crystal growth of xPb(In1/2Nb1/2)O3-yPb(Mg1/3Nb2/3)-zPbTiO3 (PIMNT 100x/100y/100z) and x'Pb(Sc1/2Nb1/2)O3-y'Pb(Mg1/3Nb2/3)-z'PbTiO3 (PSMNT 100x'/100y'/100z') ternary systems was investigated by the solution Bridgman method using PbO-B2O3 flux. A PIMNT single crystal 25 mm in diameter and 30 mm in length was grown at the bottom of a platinum crucible; the highest temperature was 1250°C and the growth rate was 0.4 mm/h. On the other hand, the PSMNT single crystals were multi nucleated under the same growth conditions. The results obtained using an electron probe microanalyzer (EPMA) revealed that Ti content increased gradually from the crystal part near the bottom of the crucible for the PIMNT and PSMNT single crystals. Although the In/Mg ratio was relatively constant in the PIMNT, the Sc/Mg ratio varied considerably in the PSMNT crystals. The Curie temperature, Tc, of the PIMNT single crystal ranged from 181°C to 196°C. The dielectric constant after poling, ε33T/ε0=3,630, coercive field of Ec=7.0 kV/cm, electromechanical coupling factors sliver mode, k'33=80.3%, and frequency constant, N'33r=1,110 Hz·m, were confirmed for the PIMNT single crystal with Tc=191°C.

Crystal Growth and Some Properties of Lead Indium Niobate-Lead Titanate Single Crystals Produced by Solution Bridgman Method

A single crystal about 15 mm in diameter and 10 mm in length of the lead indium niobate-lead titanate, (1-x)Pb(In1/2Nb1/2)O3–xPbTiO3[PIN–PT(1-x/x)] solid solution system near a morphotropic phase boundary was obtained by the solution Bridgman method using PbO–B2O3 flux. X-ray diffraction study reveals that the ingot cut perpendicularly to the cylindrical as-grown PIN–PT(63/37)(the starting composition) single crystal length exhibits the (110) plane of the perovskite phase, and the wafers cut 2 mm and 10 mm from the bottom of the cylindrical PIN–PT single crystal exhibit the rhombohedral phase and tetragonal one at room temperature, respectively. The crystal growth was almost along the [110] direction. The Ti contents x of these wafers cut at 2 mm and at 10 mm were determined by Inductive Charge Plasma (ICP) chemical analysis to be 0.31 and 0.35, respectively. The Ti content of the as-grown PIN–PT(63/37)(the starting composition) single crystal was found to increase with growth away from the nucleation point. For x=0.31, the relative permittivity εr has a peak (37000 at 10 kHz) at the Curie temperature Tc, 300°C and then a shoulder at the ferroelectric rhombohedral to tetragonal phase transition temperature, 120°C with cooling. For x=0.35, the εr has a peak (25000 at 10 kHz) at Tc, 313°C.

Growth of High‐Quality Pb((Zn1/3Nb2/3)0.91Ti0.09)O3 Single Crystals by Excess ZnO Addition

A high‐quality single crystal of Pb((Zn1/3Nb2/3)0.91Ti0.09)O3 (PZNT 91/9), 40 mm in diameter and 20 mm in length, was successfully grown using the solution Bridgman method with a slight excess amount of ZnO. High‐quality wafers were sliced from the light‐brown single crystal. No PbO inclusions or opaque areas were observed in the transparent wafers. An array probe for echocardiography was constructed with the single‐crystal wafer, and its superior performance was demonstrated.

Growth of 3-in single crystals of piezoelectric Pb[(Zn 1/3Nb 2/3) 0.91Ti 0.09]O 3 by the supported solution Bridgman method

Piezoelectric single crystals of Pb[(Zn 1/3Nb 2/3) 0.91Ti 0.09]O 3 were grown by the one batch solution Bridgman method in a Pt crucible supported at the bottom by an insulator stand. The diameter and height of the crystals were approximately 75 and 55 mm, respectively, and the average weight was approximately 1000 g. No Pt inclusion was detected. Variations of Ti 4+ concentration along with the growth direction and in the wafer were investigated by X-ray fluorescence (XRF) analysis.

Piezoelectric single crystal Pb[(Zn 1/3Nb 2/3) 0.93Ti 0.07] O 3 (PZNT 93/7) for ultrasonic transducers

Pb [(Zn 1/3Nb 2/3) 0.93Ti 0.07] O 3(PZNT 93/7) single crystals 40 mm diameter were grown by solution Bridgman method. The prerequisites for growth of PZNT 93/7 single crystals are higher melting temperature, longer melting time than Pb [(Zn 1/3Nb 2/3) 0.91Ti 0.09] O 3 (PZNT 91/9) and ZnO addition. The Curie temperature is 155–175°C and the temperature, which corresponds to rhombohedral–tetragonal phase change, T rt, is higher than 110°C for PZNT 93/7 single crystal. The T rt corresponds to the degradation boundary temperature of electromechanical coupling coefficient, k 33, also. The sensitivity degradation of ultrasonic transducers using PZNT 93/7 single crystal can be prevented up to a high temperature, about 100°C. Therefore, the results indicated that PZNT 93/7 has good potential for application in the mass production of ultrasonic transducers.

Piezoelectric Pb[(Zn 1/3Nb 2/3) 0.91Ti 0.09]O 3 single crystals with a diameter of 2 inches by the solution Bridgman method supported on the bottom of a crucible

Piezoelectric Pb[(Zn 1/3Nb 2/3) 0.91Ti 0.09]O 3 (PZNT 91/9) single crystals with a diameter of 2 inches were grown from a solution by the Bridgman method with a PbO flux supported on the bottom of the crucible. This type of Bridgman method is more suitable for growing large/heavy crystals than the suspended type of Bridgman method. The crystals were grown in a platinum crucible and the growth speed was 0.20–0.50 mm/h. The obtained crystals were about 2 inches in diameter×1/2 inches in length (weight=368 g) and were a light brown color. Forty-two pieces of 0.4 mm wafer were obtained from this crystal. The quality of some wafers was excellent. From these results, it is reasonable to expect that mass production of large crystals of PZNT 91/9 can be realized in the near future.

Influence of sulphur on the electrical and optical properties of p-type CuIn(SxSe1−x)2 single crystals

The substitution of selenium by sulphur in thin film solar cells still is a challenging topic. The origin of the related disadvantageous electrical properties to date is not well understood. A distinction of effects caused by preparation technology and intrinsic material properties is difficult. Therefore, comparative studies on bulk single crystals should provide valuable information. We grew CuIn(SxSe1−x)2 crystals by the solution Bridgman method using CuSe as a solvent. The crystals were analysed by x-ray diffraction, photoluminescence and Hall-effect measurements and turned out to be of an excellent electrical homogeneity. The temperature dependent carrier concentrations can be well explained by assuming a two acceptor and one donor model. The activation energies of the acceptor levels clearly shift to higher values when selenium is substituted by sulphur. This is confirmed by photoluminescence measurements, which reveal an acceptor to band edge transition shifting to higher energies with increasing sulphur content.

Thermal Analyses of CuInGeSe4 Quaternary Compound for Crystal Growth by Solution Method

In order to synthesize the single phase of quaternary compound CuInGeSe4 from the stoichiometric melt, the pseudo-binary phase diagram of the CuInSe2-GeSe2 system was investigated. The CuInGeSe4 phase was found to be formed through a peritectic reaction between CuInSe2 and liquid phase. We also constructed the phase diagrams of the pseudo-binary of the CuSe-CuInGeSe4, InSe-CuInGeSe4 and GeSe-CuInGeSe4 systems to find the solvents for firstly crystallizing CuInGeSe4 single phase. The results by the solution Bridgman method showed that CuSe is more suitable as a solvent to grow CuInGeSe4 single crystals.

Crystal Growth and Mechanical Properties of Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 Single Crystal Produced by Solution Bridgman Method

High-quality, 40-mm-diameter piezoelectric Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 single crystals (PZNT91/9) were successfully grown by the solution Bridgman method. Vickers hardness and fracture toughness of a PZNT91/9 wafer cut from a crystal were investigated by a microindentation technique. The Vickers hardness of PZNT91/9 was 2.6 GPa (transparent area) and 2.2 GPa (opaque area). The Vickers hardness of the transparent area in PZNT91/9 was equivalent to that of PZT ceramic. The fracture toughness of the transparent area of PZNT91/9 was markedly different depending on the domain direction: KIC=0.80 MPa·m1/2 (vertical to the domain wall); and KIC=0.38 MPa·m1/2 (parallel to the domain wall). Although the fracture toughness of PZNT91/9 is smaller than that of PZT ceramic, it is possible to cut the crystals for fine-pitch dicing, as required to produce array-type medical transducers, without serious problems.

Growth of Pb[(Zn1/3Nb2/3)0.91Tio.09]03 Single Crystal of Ultrasonic Transducer for Medical Application

Single crystals of Pb[(Znl/3Nb2/3)0o91Tio009]03 (PZNT 91/9) were grown by the Solution Bridgman method using a PbO-based flux. The crystals were about 40 m min diameter X 25 mm in size and had a light brown color. The properties of these single crystals satisfy the requirements for array-type transducers in echocardio-graphs, a type of medical diagnostic equipment. Compared with other piezoelectric materials, PZNT 91/9 is a superior piezoelectric material for ultrasonic diagnostic cardiac probes.

Crystal Growth and Electrical Properties of Pb((Zn1/3Nb2/3)0.91Ti0.09)O3 Single Crystals Produced by Solution Bridgman Method

Piezoelectric Pb((Zn1/3Nb2/3)0.91Ti0.09)O3 (PZNT 91/9) single crystals 40 mm in diameter were successfully grown from solution by the Bridgman method with a PbO flux. The crystals were grown in a platinum crucible heated to 1130°C. Growth rate was 0.35 mm/h. The obtained crystals were ~40 mm in diameter 20 mm in length and were a rust‐brown color. The Curie temperature, TC, ranged from 175° to 185°C, and the dielectric constant before poling at room temperature was 2000‐8900 within a wafer. After electrical poling, specimens had electromechanical coupling coefficients in rectangular bar mode, k33´, of 79%‐88%, which were larger than for PZT ceramics (k33´ < 70%). These PZNT 91/9 single crystals grown by the Bridgman process satisfy the requirements for array‐type transducers used in echocardiographic equipment. Results confirm that the Bridgman method is useful for mass‐producing large crystals of PZNT 91/9.

Phase diagrams of the (Cu 2Se, CuSe)–CuGaSe 2 system and the crystal growth of CuGaSe 2 by the solution method

The pseudo-binary phase diagrams of the Cu 2Se–CuGaSe 2 and CuSe–CuGaSe 2 systems have been investigated for growing single crystals of CuGaSe 2 with high quality. When Cu 2Se is chosen as a solvent, a CuGaSe 2 single crystal was grown from a solution containing 55 mol% CuGaSe 2, while in the case of a CuSe solvent, it was grown from a solution containing 58 mol% CuGaSe 2. The crystal growth of CuGaSe 2 has been attempted from each solution by the so-called solution Bridgman method. The composition of the single crystals precipitated from the two solutions is nearly stoichiometric (Cu : Ga : Se=1 : 1 : 2). In conclusion, large single crystals can be better grown from CuSe solvent than from Cu 2Se solvent.