{{Short description|Critical transition region in ferroelectric materials}}
'''Morphotropic phase boundary''' (MPB) is a critical transition region in the composition phase diagram of a piezoelectric or ferroelectric material, where the crystal structure of the material changes abruptly and the electromechanical properties are maximal.<ref>{{Citation |last=Teh |first=Ying Shi |title=Understanding the morphotropic phase boundary of perovskite solid solutions as a frustrated state |date=2020-11-02 |url=http://arxiv.org/abs/2011.00752 |access-date=2026-03-21 |publisher=arXiv |doi=10.48550/arXiv.2011.00752 |id=arXiv:2011.00752 |last2=Li |first2=Jiangyu |last3=Bhattacharya |first3=Kaushik}}</ref><ref>{{Cite journal |last=Ahart |first=Muhtar |last2=Somayazulu |first2=Maddury |last3=Cohen |first3=R. E. |last4=Ganesh |first4=P. |last5=Dera |first5=Przemyslaw |last6=Mao |first6=Ho-kwang |last7=Hemley |first7=Russell J. |last8=Ren |first8=Yang |last9=Liermann |first9=Peter |last10=Wu |first10=Zhigang |date=2008 |title=Origin of morphotropic phase boundaries in ferroelectrics |url=https://www.nature.com/articles/nature06459 |journal=Nature |language=en |volume=451 |issue=7178 |pages=545–548 |doi=10.1038/nature06459 |issn=1476-4687}}</ref><ref>{{Cite journal |last=Cordero |first=Francesco |date=2015-12-02 |title=Elastic Properties and Enhanced Piezoelectric Response at Morphotropic Phase Boundaries |url=https://www.mdpi.com/1996-1944/8/12/5452 |journal=Materials |language=en |volume=8 |issue=12 |pages=8195–8245 |doi=10.3390/ma8125452 |doi-access=free|issn=1996-1944 |archive-url=http://web.archive.org/web/20250515203602/https://www.mdpi.com/1996-1944/8/12/5452 |archive-date=2025-05-15}}</ref> It is an important parameter in the design of nonlinear materials with highly nonlinear dielectric and piezoelectric properties.<ref>{{Cite web |title=Morphotropic Phase Boundary - an overview {{!}} ScienceDirect Topics |url=https://www.sciencedirect.com/topics/engineering/morphotropic-phase-boundary |access-date=2026-03-21 |website=www.sciencedirect.com}}</ref> In ferroelectric polymers, it is used to enable a large piezoelectric effect.<ref name=":0">{{Cite journal |last=Liu |first=Yuquan |last2=Tong |first2=Hui |last3=Li |first3=Chenyi |last4=Qi |first4=Wei |last5=Zhou |first5=Huamin |last6=Liu |first6=Yang |date=2025 |title=Morphotropic Phase Boundary in Irradiated Ferroelectric Polymers |url=https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.202502099 |journal=Advanced Materials |language=en |volume=37 |issue=34 |article-number=2502099 |doi=10.1002/adma.202502099 |issn=1521-4095}}</ref> It is also found in thermoelectric materials.<ref>{{Cite journal |last=Liang |first=Jiasheng |last2=Liu |first2=Jin |last3=Qiu |first3=Pengfei |last4=Ming |first4=Chen |last5=Zhou |first5=Zhengyang |last6=Gao |first6=Zhiqiang |last7=Zhao |first7=Kunpeng |last8=Chen |first8=Lidong |last9=Shi |first9=Xun |date=2023-12-19 |title=Modulation of the morphotropic phase boundary for high-performance ductile thermoelectric materials |url=https://www.nature.com/articles/s41467-023-44318-4 |journal=Nature Communications |language=en |volume=14 |issue=1 |page=8442 |doi=10.1038/s41467-023-44318-4 |issn=2041-1723}}</ref>
In piezoelectric polymers, the morphotropic phase boundary refers to the phase transition between tetragonal and rhombohedral ferroelectric phases following a change in composition or mechanical pressure. in some piezoelectric materials like polarized organic piezoelectric materials, it is either not found or rarely found. In these materials, MPB can be induced by using some mechanism, to achieve high performance of piezoelectric effects.<ref>{{Cite journal |last=Gao |first=Fangfang |last2=Zhao |first2=Xuan |last3=Xun |first3=Xiaochen |last4=Huang |first4=Houbing |last5=Shi |first5=Xiaoming |last6=Li |first6=Qi |last7=Liu |first7=Fang |last8=Gao |first8=Peng |last9=Liao |first9=Qingliang |last10=Zhang |first10=Yue |date=2023-06-13 |title=Morphotropic Phase Boundary in Polarized Organic Piezoelectric Materials |url=https://link.aps.org/doi/10.1103/PhysRevLett.130.246801 |journal=Physical Review Letters |language=en |volume=130 |issue=24 |doi=10.1103/PhysRevLett.130.246801 |issn=0031-9007}}</ref><ref name=":0" />
== References == <references /> {{Physics-stub}}
Category:Materials science Category:Ferroelectric materials Category:Piezoelectric materials Category:Thermoelectricity