Magnetocaloric Effect in Fe-Ni-Zr Alloys Prepared by Using the Rapidly-quenched Method

Nguyen Huy Dan,Nguyen Huu Duc,Tran Dang Thanh,Nguyen Hai Yen,Ngac An Bang,Do Thi Kim Anh,판더롱,유성초 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12

Fe90−xNixZr10 (x = 0, 5, 10, 15, 20 and 25) ribbons with various thicknesses were prepared byusing a melt-spinning technique. The Curie temperature, TC, of the alloys dramatically decreasedfrom 960 K to room temperature at high quenching rates. When the alloys had an amorphousstructure, their TC strongly depended on the Ni concentration. The maximum entropy change,|Sm|max, with H = 12 kOe, of the alloys was around 1 J·kg−1K−1 at room temperature. Onthe other hand, the full width at half maximum the entropy-change peak was quite large, 85 K,which was suitable for applications in magnetic refrigerators at room temperature.

THI의 의미론적 논법

Nguyen Duc Dan 조선대학교 국제문화연구원 2009 국제문화연구 Vol.2 No.1

After giving a brief review of the different ideas of the Vietnamese linguists about the word THI, the author presents his judgment about this word as the followings: 1. First as all, the word THI is a conjunction in the structure of the complex sentences which indicates the relationship between condition and result. This structure is a kind of cause - effect one which reflects structure of logic statement “a ⇒ b”. So, we could apply the inferences of prepositional logic to recognize the implication of the sentences which includes the word thi. The most useful inferences are: - The inference by Modus ponens (sufficient condition): (MP) ((x ⇒ y) & x) ⇒ y - The inference by Modus tollens (necessery condition): (MP) ((x ⇒ y) & ~y) ⇒ ~x - The inference by Hypothetical Syllogisms: (HS) ((x ⇒ y) & (y ⇒ z)) ⇒ (x ⇒ z) There is a specific inference in some cases of natural languages in general and Vietnamese language in particular: a sufficient condition may be used as a necessary one. Considering this inference as MV, we have: (MV) ((x ⇒ y) & ~x) ⇒ ~y There are modal inferences for MT and MV. That is: (MT₁) ((x ⇒ y) & muốn ~y) ⇒ đừng ~x / không nên x (MT₂) ((x ⇒ y) & cần ~y) ⇒ phải ~x / không thể x (MV₁) ((x ⇒ y) & muốn ~x) ⇒ đừng ~y / không nên y 2. As a follow-up to the inferences, author presents a general method to investigate the implications in the complex sentences which include the structure of “nếu …thì”. After that, with a series examples, the author demonstrates indirect speech acts of these complex sentences as follows: - Vow, promise: ‘Lạy ông bà, chúng con có biết cái ví tiền của ông mật ngang mũi dọc thế nào thì chúng con cú chết một đời cha ba đời con!’ (NCH). (We (I) swear to you, grandpa, grandma, if we knew anything about the money in your wallet, we (I) would die, our kids would die, and our grandkids would die). - Advice: ‘Nếu ngài không ra tranh cử thì còn ai nữa?’ (If you don't want to run for office, then who will?) - Forbiddance, intimidation: ‘Con mà lấy nó thì đừng bao giờ về nhà này nữa. (If you marry him, don't ever come back to this house). - Assessment, appraisement: She loves you unless the sun rises in the West // Giá Ba chăm học, anh ấy đã đậu đại học (If Ba had studied hard, he would have passed the examination to the university). - Affirmation: ‘Nhưng chẳng tin vào bùa thì còn biết làm gì nữa’ (CĐBT, NNT) If you don't believe in amulet what else? - Announcement: ‘Làm vậy thể nào anh cũng sẽ bị ngồi tù đấy' (If you do that, and then definitely you’ll go to jail). - Proposition, requirement: ‘Nếu cậu không giúp mình chuyện này thì đừng coi mình là bạn nữa.’ If you don’t help me this time, then don’t consider me as your best friend. - Refusal: Tôi giúp anh, sếp biết được thì tôi mất việc. (I could help you, but if the boss knew, I would loss my job). 3. The author uses the inferences MP, MT, MV for investigating the pragmatic implication of the pair utterances of conversation. This pragmatic implication “conceals” in the later utterance which includes the word THI and indicates indirect speech acts such as affirmation, assessment, announcement, refusal, advice… Examples: 1) - Can I park my car here? - Yes, if you want to pay a fine 2) - Why did you beat the young brother? - I didn’t beat him because he is good-mannered) - Sao không cho anh ấy mượn tiền? - Giá như anh ấy giúp đỡ những người khác thì tôi đã cho mượn rồi (- Why didn’t you lent the money to him? - If he had helped others, I would have lent the money to him.) 3) - Em không tin chồng em có bồ. Họa có đứa điên thì nó mới theo không anh ta. - Vậy à? Thế mà bây giờ có đứa đang điên đấy. - (I don’t believe my husband is having a girlfriend. Most likely, she is not too crazy to get involved with him for nothing. - Oh, really? Look, who is a crazy one right now?) 4. Idioms with the word THI In conversation, there are utterances expressing speech acts which become the particular language patterns. A first speech act leads to second speech act. Hence, this is a cause-effect relation. Step by step, these patterns become to idioms indicating a specific speech act even though it doesn’t contain specific content. There are some idioms with the word THI that indicate a specific speech act: ‘A thì cũng x’. This is a rejection, a refusal to accept a role or influence (and consequence) of A to make an appearance x. ‘Không A thì cũng B’. This is a assertion that affirms an object having the property A or B (that a few lower than A). “A thì có!”. This is an affirmation. In that A is affirmed and an implicit B (in previous utterance) is rejected. “y thì không”. This is an acceptance. In that, we are agreed with one’s opinion about x although we affirm y is the same as x. ‘A(x) thì A’. This accepts a suggesting to realize A. ‘A thì phải’: This is a predict A. 5. The word THI and operation of division of a set The concept of word THI considering as a operation of division of a set permits us to explain several phenomena in Vietnamese language related to the word thì. In addition, other functions of THI are investigated.

Large Magnetocaloric Effect Around Room Temperature in Amorphous Fe-Gd-Zr Alloy Ribbon with Short-Range Interactions

Thanh, Tran Dang,Yen, Nguyen Hai,Duc, Nguyen Huu,Phan, The-Long,Dan, Nguyen Huy,Yu, Seong-Cho Springer-Verlag 2016 Journal of electronic materials Vol.45 No.5

Magnetic and magnetocaloric properties of Ni-Ag-Mn-Sn ribbons and their composites

Thanh, Tran Dang,Duc, Nguyen Huu,Dan, Nguyen Huy,Mai, N.T.,Phan, T.L.,Oh, S.K.,Yu, Seong-Cho Elsevier 2017 Journal of Alloys and Compounds Vol.696 No.-

<P><B>Abstract</B></P> <P>In this work, we have investigated the influence of Ag-doping on the magnetic and magnetocaloric effect (MCE) of Ni<SUB>50-x</SUB>Ag<SUB>x</SUB>Mn<SUB>37</SUB>Sn<SUB>13</SUB> ribbons with <I>x</I> = 1, 2, and 4, which were prepared by a melt-spinning method. With increasing Ag concentration, a systematic decrease in the antiferromagnetic interaction and in the magnetic phase transition temperatures was observed. Analyses of the critical behavior based on the Banerjee criterion and scaling hypothesis for <I>M</I>(<I>H</I>, <I>T</I>) data near the ferromagnetic-paramagnetic transformation prove an increase of Ag favors establishing long-range ferromagnetic interactions in the austenitic phase. The temperature and magnetic field dependences of magnetic entropy change, Δ<I>S</I> <SUB>m</SUB>(<I>T</I>, <I>H</I>) were investigated via isothermal magnetization measurements. Interestingly, these samples exhibit a MCE at room-temperature with the Δ<I>S</I> <SUB>m</SUB>(<I>T</I>) curves distributed over a quite wide temperature range. To enhance the relative cooling power (RCP) value and to extend the magnetic phase transition region, we have prepared the composites in the form of the layered material samples based on ribbons obtained above. Under Δ<I>H</I> = 10 kOe, the maximum value of Δ<I>S</I> <SUB>m</SUB> (denoted as |Δ<I>S</I> <SUB>max</SUB>|) at around room-temperature is 1.08 J kg<SUP>−1</SUP> K<SUP>−1</SUP>, corresponding to RCP = 51.8 J kg<SUP>−1</SUP>, which is about 10% higher than that obtained from a separate sample. Additionally, we also pointed out that the dependences of |Δ<I>S</I> <SUB>max</SUB>| on Δ<I>H</I> at around room-temperature for samples obey a power law, |Δ<I>S</I> <SUB>max</SUB>| = <I>a</I> × Δ<I>H</I> <SUP>n</SUP>, and all the Δ<I>S</I> <SUB>m</SUB>(<I>T</I>, <I>H</I>) data obey completely a universal master curve.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An increase of Ag in Ni<SUB>1-x</SUB>Ag<SUB>x</SUB>Mn<SUB>37</SUB>Sn<SUB>13</SUB> ribbons favors establishing long-range FM order in the austenitic phase. </LI> <LI> High magnetic entropy change, wide operative temperature range, and high RCP value around room-temperature. </LI> <LI> The composite of Ni<SUB>1-x</SUB>Ag<SUB>x</SUB>Mn<SUB>37</SUB>Sn<SUB>13</SUB> ribbons exhibits higher RCP value and extends the magnetic phase transition region. </LI> <LI> Field dependence of |Δ<I>S</I> <SUB>max</SUB>| can be expressed by the power law. </LI> <LI> All the Δ<I>S</I> <SUB>m</SUB>(<I>T, H</I>) data around room temperature are followed a universal master curve. </LI> </UL> </P>