Perovskite-Like Layered Structure A2B2O7 Ferroelectrics and Solid Solutions.

In this project, the ferroelectric materials Pr2Ti2O7, La2Ti2O7, Sr2Nb2O7, La2-xCexTi2O7 (x=0.15, 0.25, 0.35), Nd2-xCexTi2O7 (x=0.05, 0.25, 0.5, 0.75) and Sr2-xBaxNb2O7 (x=0.1, 0.2, 0.3, 0.4, 0.5) were investigated. They have a provskite-like layered structure (PLS), and are well known for their super-high Curie points (>1200 ˚C). Their ceramics were fabricated using Spark Plasma Sintering. For Pr2Ti2O7, single phase, dense and textured ceramics were prepared. The Curie point is greater than 1560 °C which is the highest known Curie Point so far for ferroelectric materials. Pr2Ti2O7 was shown for the first time to be ferroelectric because it showed piezoelectric activity after poling. For the La2-xCexTi2O7 solid solution system, the ferroelectric and dielectric properties of cerium (Ce) substituted La2Ti2O7 (LTO) were investigated. The solubility limit of Ce in La2-xCexTi2O7 was found to be between 0.35 and 0.5 supported by XRD results. The a-, b- and c-axes of the unit cell decrease with increasing Ce substitution. The Curie points (Tc) of La2-xCexTi2O7 (x=0, 0.15, 0.25, 0.35) also decreases. The dielectric constant and loss increase with increasing Ce substitution. Electrical resistivity decreases due to Ce substitution. Cerium can increase the d33 of La2Ti2O7. The highest d33 was 3.9 ± 0.1pC/N for La1.85Ce0.15Ti2O7. In the Nd2-xCexTi2O7 system, the cell volume increases from Nd2Ti2O7 to Nd1.25Ce0.75Ti2O7 and the Curie point (Tc) decreases with Ce increase. For the Sr2-xBaxNb2O7 solid solution system, the effect of Ba substitution on the structure and ferroelectric properties of Sr2-xBaxNb2O7 (x<1.0) was investigated. The a-, b-, c- axes and cell volume increase with Ba addition because Ba2+ is a relatively large ion. A atomic displace move model was developed to explain the spontaneous lattice strain, spontaneous polarization and Curie point change in the orthorhombic phase (Cmc21) with increasing Ba substitution. The critical point of Sr2-xBaxNb2O7 solid solution (x<0.6) was determined by XRD and was supported by the XPS spectra of Ba 2p and O 1s. Textured ceramics of Sr2-xBaxNb2O7 compounds were prepared using the spark plasma sintering technique and the piezoelectric activity can be improved by Ba substitution, which increases the domain switch mobility. The highest d33 was measured as 3.6± 0.1pC/N for Sr1.8Ba0.2Nb2O7. The thermal depoling behaviors of La2Ti2O7, and Sr2Nb2O7 were investigated due to their relatively high d33 piezoelectric constant and high Curie point. Both of them have a high resistance to thermal depoling, especially La2Ti2O7. Ginzburg - Landau theory was used to explain their behavior. The electric resistivity degradation of Sr2Nb2O7 was studied at different temperatures, and it was found to be stable below 800 °C.Chinese Scholarship Council

The Mind of the New Socialist Student in the Chinese Revolutionary Imagination, 1949-1958

Between 1949 and 1958, the nascent Peoples Republic of China witnessed a radical shift of knowledge about the human mind that transformed pedagogy. Against the Cold War and the changing Sino-Soviet relation, Chinese psychologists progressively repudiated American and Soviet schools for their shared deterministic philosophy and disinterest in human agency and class struggle. In light of this critique, educators abandoned psychological science as the basis of pedagogy and endeavored to create a supreme new socialist student to meet Chinas economic and political agendas. This dissertation explores this exteriorization epistemic transition by juxtaposing psychology and education. Taking advantage of so far untapped archival and published sources, this dissertation explores how psychologists, educators, and students navigated between a utopian communist dream and Chinas harsh socioeconomic reality in the creation of the new socialist student ideal. Chapter One Wrestling with Human Nature argues that the critique of psychology instantiated Chinas progressive ethos that, in the endeavor of transforming human mentality, rejected scientific discovery of mental laws. Chapter Two Laborizing Education argues that students faced excessive academic and labor tasks due to Chinas pursuit of post-war recovery, of success in Cold War competition, and of forestalling future labor-based class stratification. Chapter Three Engendering Citizenship scrutinizes how educators tapped into students subjectivity to produce a new citizenship identity capable of dismantling existing social relations

Unsettled Belongings: Chinese Immigrants’ Mental Health Vulnerability as a Symptom of International Politics in the COVID-19 Pandemic

The COVID-19 pandemic has led to unique mental health challenges for Chinese immigrants due to their cultural, social, and political ties with China, which responded to COVID-19 with controversial measures amid tensions with the Western world. These challenges manifest in three conditions at a time of crisis: racism that associates overseas Chinese with the coronavirus, Chinese immigrants’ “double unbelonging” with regard to both host societies and China, and social disapproval of political criticism among overseas Chinese. This article examines these three conditions by drawing on ethnography conducted in Canada as well as international online media. It uses theories in humanistic psychology, existential psychology, and hermeneutics to explain how, for Chinese immigrants, international political tensions are implicated in a range of mental health–related phenomena including identity, belonging, self-consciousness, shame, depression, and agency. Meanwhile, it offers theoretical discussions of how to make humanistic psychology more capable of addressing social and political issues

Mieke Matthyssen: Ignorance is Bliss—The Chinese Art of Not Knowing

Matthyssen’s monograph has an intriguing title: Ignorance is Bliss: The Chinese Art of Not Knowing. The art of not knowing is encapsulated in a pithy Chinese expression: Nande hutu (难得糊涂), which literally translates to “Hard to attain muddleheadedness”. In practice, Nande hutu entails deliberate performance of not knowing, or “playing dumb”, for one to cope with challenging circumstances. For example, a government official might pretend not to see corruption so as to keep a distance from it. More than a survival strategy, Nande hutu also allows one to maintain moral integrity or even achieve spiritual transcendence. As simple as the notion of Nande hutu might appear to be, it requires steadfast self-cultivation in the long run and skilful self-control during social interactions. For all these reasons, Nande hutu became a maxim that for centuries inspired Chinese individuals from varied walks of life. Capturing the sheer complexity of Nande hutu, Matthyssen treats it as the entrance into a labyrinth of Chinese philosophy, politics, social relations, and a cultural history spanning from ancient times to today

Flow Pattern and Mixing Characteristics of Highly Viscous Fluids in a Dynamic Mixer

Peer reviewe