• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
• /
• pp.171-172
• /
• 2006

The effect of the preparation factors, such as the feeding mode and rate of raw materials, the reaction temperature and the surfactant on the size distribution of molybdenum trioxide particle were investigated by orthogonal test. The optimum conditions for the preparation of $MoO_3$ precursors are as following; opposite feeding fast, reaction temperature of $60^{\circ}C$ and adding dispersant.

• 한국분말재료학회지
• /
• 제27권5호
• /
• pp.394-400
• /
• 2020

Molybdenum trioxide (MoO₃) is used in various applications including sensors, photocatalysts, and batteries owing to its excellent ionic conductivity and thermal properties. It can also be used as a precursor in the hydrogen reduction process to obtain molybdenum metals. Control of the parameters governing the MoO₃ synthesis process is extremely important because the size and shape of MoO₃ in the reduction process affect the shape, size, and crystallization of Mo metal. In this study, we fabricated MoO₃ nanoparticles using a solution combustion synthesis (SCS) method that utilizes an organic additive, thereby controlling their morphology. The nucleation behavior and particle morphology were confirmed using ultraviolet-visible spectroscopy (UV-vis) and field emission scanning electron microscopy (FE-SEM). The concentration of the precursor (ammonium heptamolybdate tetrahydrate) was adjusted to be 0.1, 0.2, and 0.4 M. Depending on this concentration, different nucleation rates were obtained, thereby resulting in different particle morphologies.

• Korean Chemical Engineering Research
• /
• 제57권6호
• /
• pp.891-897
• /
• 2019

본 연구에서는 Phosphoric acid ($H_3PO_4$)와 Vanadium (V) pentoxide ($V_2O_5$), Molybdenum (VI) trioxide ($MoO_3$)으로 부터 조성을 달리하여, heteropoly acid의 PVMo 촉매를 활성탄 지지체에 담지하였다. 촉매의 반응성 조사를 위해, 기상의 포름알데히드를 $140^{\circ}C$의 온도에서 1시간 동안 반응시켰다. 반응전후의 촉매는 XRD와 BET 분석을 수행하였으며, 촉매의 산도 측정을 위해 $NH_3-TPD$을 수행하였다. 포름알데히드의 전환율은 $MoO_3$와 $H_3PO_4$ 성분이 감소하고 $V_2O_5$ 성분이 증가함에 따라 증가하였다. 대부분의 촉매에서 비교적 낮은 촉매 결정성이 관찰되었으며, 비표면적은 반응후 다소 감소하는 것으로 나타났다. $NH_3-TPD$ 분석 결과, $400^{\circ}C{\sim}500^{\circ}C$에 해당하는 강한 산점의 비율이 $MoO_3$와 $H_3PO_4$ 성분의 함량이 감소하고 $V_2O_5$ 성분의 함량이 증가함에 따라 증가하였다. 이러한 강한 산점의 비율이 포름알데히드의 전환율에 영향을 미치는 것으로 나타났다.

• 자원리싸이클링
• /
• 제18권5호
• /
• pp.19-25
• /
• 2009

몰리브덴 산업에서 가장 중요한 광물인 휘수연석($MoS_2$) 정광은 일련의 산화배소정제 공정을 통하여 공업용 산화몰리브덴(technical grade $MoO_3$)으로 제조되어 각종 몰리브덴 화합물의 중요한 원료로서 사용된다. 본 연구에서는 저품위 휘수연석 정광의 산화배소 특성을 조사하였다. 실험은 0.08 atm~0.21 atm의 산소분압과 793~823 K의 배소은도 범위에서 TGA 장비를 사용하여 수행하였으며, 사용한 휘수연석 정광의 입자크기는 평균 $67\;{\mu}m$ 이다. 실험 결과 산화배소 온도 823 K, 시간 60분에서 95% 이상의 휘수연석이 산화몰리브덴으로 전환되는 것으로 나타났다. 또한 Jander 식이 저품위 몽골산 휘수연석 정광의 산화배소 속도 데이터를 분석하는데 유용한 것으로 분석되었으며, 산소 분압에 대해서는 0.11 차인 것으로 조사되었다.

• Journal of Electrochemical Science and Technology
• /
• 제7권2호
• /
• pp.170-178
• /
• 2016

Composited molybdenum oxide and amorphous carbon (MoO₃/C) as anode material for lithium ion batteries has been successfully synthesized by calcining polyaniline (PANI) doped with ammonium heptamolybdate tetrahydrate (AMo). The as prepared electrode material was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and field emission scanning electron microscopy (FE-SEM). The electrochemical performance of the anode was investigated by galvanostatic charge/discharge, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The MoO₃/C shows higher specific capacity, better cyclic performance and rate performance than pristine MoO₃ at room temperature. The electrochemical of MoO₃/C properties at various temperatures were also investigated. At elevated temperature, MoO₃/C exhibited higher specific capacity but suffered rapidly declines. While at low temperature, the electrochemical performance was mainly limited by the low kinetics of lithium ion diffusion and the high charge transfer resistance.

• Archives of Metallurgy and Materials
• /
• 제66권4호
• /
• pp.991-995
• /
• 2021

In this paper, synthesize MoO₃ particles with various particle properties by control growth influence factors was mainly studied. The experimental conditions were established in molar ratio of Mo:urea and pH levels. The plate-type of MoO₃ particles were formed without proceeding any established conditions, but the rod-shape particles were formed by adjusting molar ratio of Mo:urea. Also, different ranges of the particle size were formed by adjusting experimental conditions. Through the results, it was confirmed that particles with a size in the range of 300 ~ 400 nm were obtained by adjusting precursor concentration and the micrometer size of particles were formed by increase pH levels. The properties of the particles formed accordingly by setting various factors that can affect the growth process of MoO₃ particle was analyzed as variables and the particle growth behavior was also observed.

• 한국자원리싸이클링학회:학술대회논문집
• /
• 한국자원리싸이클링학회 2005년도 추계정기총회 및 제26회 학술발표대회 고분자리싸이클링기술 특별심포지엄
• /
• pp.153-157
• /
• 2005

• 한국입자에어로졸학회지
• /
• 제9권1호
• /
• pp.31-36
• /
• 2013

In this study, Mo metal powder was prepared by hydrogen reduction of Mo trioxides with different purity of 2N and 3N grades. We have obtained Mo metal powder with oxygen content of 1450 ppm by hydrogen reduction and subsequent heat treatment for degassing. Using the Mo metal powder, a low-oxygen Mo ingot was prepared by repetitive vacuum arc melting. The oxygen content of the obtained Mo ingot was less than 70 ppm after vacuum arc melting for 30 min. The purity of the Mo metal powder and the ingot was evaluated using glow discharge mass spectrometry. The purity of the respective Mo ingots was increased to 3N and 4N grades from the Mo powder of 2N and 3N grades after the repetitive vacuum arc melting. The low oxygen Mo ingot thus can be used as a raw material for sputtering targets.

• Current Applied Physics
• /
• 제18권12호
• /
• pp.1592-1599
• /
• 2018

The present study deals with the effect of dual cathode buffer layer (CBL) on the performance of bilayer of 4,4'-cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine] (TAPC) and fullerene (C70)-based organic solar cell (OSC) with low donor concentration. OSC devices with CBLs have been fabricated using thermal vapor deposition technique. We report the use of lithium fluoride (LiF) and molybdenum trioxide ($MoO_3$) as CBLs. The insertion of LiF between C70 and aluminium (Al) electrode enhances the power conversion efficiency (PCE) of device from 1.89% to 2.47% but quenching of photogenerated excitons is observed at interface of C70 and LiF layers. Incorporation of $MoO_3$ between LiF and Al electrode further enhances PCE of device to 3.51%. This has also improved the material quality and device properties, by preventing the formation of gap states and diminishing exciton quenching.

• 한국재료학회지
• /
• 제25권10호
• /
• pp.547-551
• /
• 2015

The present study prepared molybdenum trioxide ($MoO_3$), the most important intermediate of molybdenum metal, by using a fluidized bed reactor for the thermal decomposition of ammonium molybdate (AM) in the presence of an air flow. During the process of fluidizing the sample inside the reactor, the reaction time and temperature were optimized with a close analysis of the X-ray diffraction (XRD) data and with thermogravimetric analysis (TGA). In particular, the temperature level, at which the AM decomposition is completed, is very important as a primary operating parameter. The analysis of the XRD and TGA data showed that the AM decomposition is almost completed at ${\sim}350^{\circ}C$ with a reaction time of 30 min. A shorter reaction time of 10 min. required a higher reaction temperature of ${\sim}500^{\circ}C$ with the same air flow rate to complete the AM decomposition. A sharp rise in the decomposition efficiency at a temperature ranging between 320 and $350^{\circ}C$ indicated a threshold for the AM decomposition. The operating conditions determined in this study can be used for future scale-ups of the process.