· Growth of New High Tc Piezoelectric Single Crystals [Relaxor-PZT Single Crystals]

PMN-PT and PZN-PT single crystals have remarkable piezoelectric properties such as k₃₃ > 0.92, d₃₃ > 2000 pC/N and unipolar strain > 1%. However, these single
crystals have some disadvantages such as low T_C, T_RT(T_DP), and E_C, as shown in table. In order to overcome the disadvantages of PMN-PT and PZN-PT single crystals, Ceracomp has developed “new high T_C piezoelectric relaxor-PZT single crystals” by using SSCG method.

· Properties of PMN-PT Crystals and PZT-5H Ceramics

	Unit	PMN-33PT Single Crystals	PZT-5H Ceramics
Dielectric Constant,k₃T	-	5,000	3,500
Dielectric Loss, tan ∂	%	< 1	< 2
Piezoelectric Constant,d₃₃	pC/N	2,000	600
Electromechanical Coupling,K₃₃	-	0.9	0.75
Frequency Constant,N₃₃	Hz-m	1,600	1,900
Coercive Electric Field, E_C	kV/cm	2.5	8.5
Curie Temp., T_c	℃	150	190
Depoling Temp., T_RT	℃	80	190

· Advantages and Disadvantages of PMN-PT Single Crystals

Advantages

- Remarkable Piezoelectric Properties -

1. Electromechanical Coupling Factor k₃₃ > 0.9
2. Piezoelectric Coefficient d₃₃ > 2,000 pC/N
3. Unipolar Strain ε > 1%

Disadvantages

1. Low Curie Temperature (T_c)
2. Low T_Rhom-Tet (T_RT) or T_DP
→ Usage Temperature Limited to T_RT or T_DP
3. Low Corecive Electric Field (E_c)

4. Low Frequency Constant (N)
5. Expensive (High Production Cost)

Solutions

- Keys for Commercialization of Crystals -

1. Development of New Compositions
→ High T_C, T_RT, E_C and others

→ Relaxor-PZT Single Crystals

2. Development of Crystal Growth Method
→ Suitable to the New Compositions
→ Suitable to Mass Production
(Low Production cost and high reproducibillty)

→ Solid-state Single Crystal Growth(SSCG) Method

↓
Mass Production of
"Relaxor -PZT" Single Crystals

Compared to PMN-PT and PZN-PT single crystals, relaxor-PZT single crystals have higher T_C,T_RT, and E_C. They also have higher phase stability and vertical MPB. And
their compositions are very similar to the compositions of the conventional PZT ceramics. Because of these advantages of relaxor-PZT compositions, relaxor-PZT
single crystals are better than PMN-PT and PZN-PT single crystals for high temperature applications.

· Development of New High Tc Piezoelectric Single Crystals
by Compositional Modification from Relaxor-PT to Relaxor-PZT

· Relaxor-PZT Single Crystals with High Tc and T_RT

조성 구배형 단결정(Growth of Single Crystals with Composition Gradient)

· Growth of a BaTiO₃ Crystal with Composition Gradient
(Undoped-. Mn-. Cr-.and Ce-doped BaTiO₃ Single Crystals)

압전 단결정 평가 기술 개발