This study investigates the effect of the microstructure of Li1.3Al0.3Ti1.7(PO4)3 (LATP), a solid electrolyte, on its ionic conductivity. Solid electrolytes, a key component in electrochemical energy storage devices such as batteries, differ from traditional liquid electrolytes by utilizing solid-state ionic conductors. LATP, characterized by its NASICON structure, facilitates rapid lithium-ion movement and exhibits relatively high ionic conductivity, chemical stability, and good electrochemical compatibility. In this study, the microstructure and ionic conductivity of LATP specimens sintered at 850, 900, and 950oC for various sintering times are analyzed. The results indicate that the changes in the microstructure due to sintering temperature and time significantly affect ionic conductivity. Notably, the specimens sintered at 900oC for 30 min exhibit high ionic conductivity. This study presents a method to optimize the ionic conductivity of LATP. Additionally, it underscores the need for a deeper understanding of the Li-ion diffusion mechanism and quantitative microstructure analysis.

Pinus densiflora is a fixed-growth coniferous species that elongates its shoot once a year and finishes growing in early summer. However, it may produce additional shoots in the same year in response to external stimuli, called abnormal shoot growth. This study investigated the effects of open-field summer warming and drought on the abnormal shoot growth of P. densiflora seedlings. In March 2022, two factorial combinations were constructed, including two temperature treatments (control and 4°C increase) and two precipitation treatments (control and drought), with five replicates for each combination. The temperature treatment was performed for 87 days from May 14 to August 8, 2022, and the precipitation treatment was performed for 33 days from May 14 to June 15, blocking 100% of the ambient rainfall. The abnormal shoot occurrence rate and leaf unfolding stages were measured in November, and the shoot and root collar diameter growth rates were calculated by comparing the seedling height and root collar diameter measured in August (after the cessation of treatment) and October (after the end of growing period) with the initial values (i.e., May 2022). The abnormal shoot occurrence rate significantly increased under the warming treatment, showing a 410.6% increase in the warming plots (38.4%) compared to the control plots (7.5%). There was no significant difference in the shoot and root collar diameter growth rate regarding warming and drought treatments. Abnormal shoots may have been affected by high temperatures by inducing early transition to the next ontogenetic stage.

NKN [(Na,K)NbO3] is a candidate lead-free piezoelectric material to replace PZT [Pb(Zr,Ti)O3]. A single crystal has excellent piezoelectric-properties and its properties are dependent of the crystal orientation direction. However, it is hard to fabricate a single crystal with stoichiometrically stable composition due to volatilization of sodium during the growth process. To solve this problem, a solid solution composition is designed (Na,K)NbO3-Ba(Cu,Nb)O3 and solid state grain growth is studied for a sizable single crystal. Ceramic powders of (Na,K)NbO3-M(Cu,Nb)O3 (M = Ca, Sr, Ba) are synthesized and grain growth behavior is investigated for different temperatures and times. Average normal grain sizes of individual specimens, which are heat-treated at 1,125 oC for 10 h, are 6.9, 2.8, and 1.6 m for M = Ca, Sr, and Ba, respectively. Depending on M, the distortion of NKN structure can be altered. XRD results show that (NKN-CaCuN: shrunken orthorhombic; NKN-SrCuN: orthorhombic; NKN-BaCuN: cubic). For the sample heat-treated at 1,125 oC for 10 h, the maximum grain sizes of individual specimens are measured as 40, 5, and 4,000 m for M = Ca, Sr, and Ba, respectively. This abnormal grain size is related to the partial melting temperature (NKN-CaCuN: 960 oC; NKN-SrCuN: 971 oC; NKN-BaCuN: 945 oC).

Pb(Zr,Ti)O3 (PZT) is used for the various piezoelectric devices owing to its high piezoelectric properties. However, lead (Pb), which is contained in PZT, causes various environment contaminations. (K,Na)NbO3 (NKN) is the most well-known candidate for a lead-free composition to replace PZT. A single crystal has excellent piezoelectric-properties and its properties can be changed by changing the orientation direction. It is hard to fabricate a NKN single crystal due to the sodium and potassium. Thus, (Na,K)NbO3-Ba(Cu,Nb)O3 (NKN-BCuN) is chosen to fabricate the single crystal with relative ease. NKNBCuN pellets consist of two parts, yellow single crystals and gray poly-crystals that contain copper. The area that has a large amount of copper particles may melt at low temperature but not the other areas. The liquid phase may be responsible for the abnormal grain growth in NKN-BCuN ceramics. The dielectric constant and tan δ are measured to be 684 and 0.036 at 1 kHz in NKN-BCuN, respectively. The coercive field and remnant polarization are 14 kV/cm and 20 μC/cm2.

지구 온난화의 영향으로 우리나라는 지난 30년동안 평균기온이 0.7℃, 겨울철에는 1.4℃가 상승하였다. 이러한 온난화로 인하여 우리나라에서는 이상기상 현상이 자주 발생하여 채소작물에 피해가 발생한다. 특히 노지에서 많이 재배되고 있는 고추, 배추 및 무는 온난화로 인하여 정식시기를 점점 앞당겨 정식후 갑작스런 저온이 오면 이들 작물의 피해가 크다. 따라서 본 실험은 저온에 따른 배추의 생육특성과 엽 세포조직에 미치는 영향을 구명하고자 실시하였다. '춘광' 배추품종을 화분에 정식한 후 노지 처리구, 무가온 하우스 및 가온하우스 처리구 등 3처리를 하였다. 그 결과, 정식후 50일의 생육은 노지처리구의 초장, 엽수, 엽록소 및 엽면적이 가온 처리구에 비해서 현저하게 떨어졌고, 특히 생체중의 경우에는 가온 처리구에 비해서 노지와 무가온 하우스 처리구가 1/3 수준으로 현저하게 낮았다. 배추의 잎이 10매 정도 생육이 되었을 때 저온에 따른 배추 잎의 피해증상은 영하 3.0℃ 조건에서는 배추 겉잎에 약간의 수침증상을 보였으나 회복되었다. 그러나 영하 7.4℃ 조건의 배추 잎은 수침증상이 심하였으며 회복되지 못하고 황색으로 변하면서 결국 잎이 고사하였다. 피해받은 잎의 엽육세포는 영하 3.0℃ 조건에서는 울타리조직과 해면조직이 약한 붕괴증상을 보였지만 어느정도 형태를 갖추고 있었는데, 영하 7.4℃ 조건에서는 세포가 동결된 후 해동되는 과정에서 세포의 막구조가 파괴되어 울타리조직과 해면조직이 완전히 붕괴되었기 때문에 세포 형태를 갖추고 있지 않았다. 따라서 배추 정식후 초기 생육 단계에서 영하 3℃까지는 비닐이나 부직포로 보온, 토양수분 조절, ABA 처리를 하여 동해를 예방할 수 있으나 영하 7℃의 저온이 발생하면 세포가 파괴되어 회복하기 어렵기 때문에 다시 심거나 또는 다른 작물로 대체하는 것이 좋을 것으로 사료되었다.

Calcium-hexaluminate phase is known to be effective for the crack shielding due to the spinel block crystal structure. In this study, we focused to the control of morphology for good damage tolerance behavior in alumina and zirconia/calcium-hexaluminate composites. Calcium-hexaluminate composites were prepared from zirconia, alumina and calcium carbornate powders. Calcium-hexaluminate phase was obtained by the solid reaction through the formation of intermediate phase . phase showed the column type abnormal grain grown behavior composed of small blocks. Due to the typical microstructure of , alumina and zirconia/calcium-hexaluminate composites provide a well controlled crack propagation behavior.

는 현재 전기 전자 부속 산업엣 필수적인 재료로서, multilayer capacitor,positive temperature coefficient(PTC) resistor, grain-boundary battier layer capacitor(GBBLC)등에 쓰이고 있다. 의 전기적 특성을 최대화하기 위해서는 미세구조가 최적화 되어야만 하는데 일반적으로 수 마이트로 이내의 작고 균일한 크기의 입자크기가 바람직하다. 그러나 계에서 화학양론의 조성이 정확

The ferroelectric properties of barium titanate strongly depend on its microstructure, in particular, grain size and distribution. During sintering, usually exhibits abnormal grain growth, which deteriorates considerably the ferroelectric properties. A typical technique to suppress the abnormal grain growth is the addition of dopants. Dopant addition, however, affects the ferroelectric properties and thus limits the application of . Here, we report a simple but novel technique to prevent the abnormal grain growth of and to overcome the limitation of dopant use. The technique consists of stepwise sintering in a reducing atmosphere and in an oxidizing atmosphere. The materials prepared by the present technique exhibit uniform grain size and high dielectric properties. The technique should provide opportunities of having -based materials with superior ferroelectric properties.

BaTiO3세라믹에서 미세구조를 조절하기 위하여 Ba/Ti비 변화에 따른 소결거동 및 비정상 입자성장에 대하여 연구하였다. 본 연구에서 사용한 BaTiO3분말은 BaCO3와 TiO2를 이용하여 일반적인 고상반응법으로 제조하였다. Ba/Ti비가 감소할수록(과잉 TiO2가 증가할수록)소결 시작온도가 낮아졌으며 치밀화가 증진되었다. 이것은 과잉 TiO2양이 증가할수록 하소된 분말의 크기가 감소되었기 때문으로 판단되며, 공융액상 형성으로 인한 액상소결에 의한 것이 아님을 알 수 있었다. 또한 과잉 TiO2양이 증가할수록 입자성장이 강력하게 억제되었으며, 이는 Ti-rich 이차상이 입자성장을 억제시킴을 의미한다. 따라서 이러한 이차상의 불균일한 분포로 인하여 비정상 입자성장이 일어나는 것으로 판단되었다.